US6985806B2 - Method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine - Google Patents

Method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine Download PDF

Info

Publication number
US6985806B2
US6985806B2 US10/624,416 US62441603A US6985806B2 US 6985806 B2 US6985806 B2 US 6985806B2 US 62441603 A US62441603 A US 62441603A US 6985806 B2 US6985806 B2 US 6985806B2
Authority
US
United States
Prior art keywords
estimated value
manifold pressure
mass flow
measured value
induction manifold
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related, expires
Application number
US10/624,416
Other languages
English (en)
Other versions
US20050021215A1 (en
Inventor
Wolfgang Stadler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Assigned to SIEMENS AKTIENGESELLSCHAFT reassignment SIEMENS AKTIENGESELLSCHAFT ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: STADLER, WOLFGANG
Publication of US20050021215A1 publication Critical patent/US20050021215A1/en
Application granted granted Critical
Publication of US6985806B2 publication Critical patent/US6985806B2/en
Adjusted expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0402—Engine intake system parameters the parameter being determined by using a model of the engine intake or its components
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0406—Intake manifold pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/04—Engine intake system parameters
    • F02D2200/0406—Intake manifold pressure
    • F02D2200/0408—Estimation of intake manifold pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/0065—Specific aspects of external EGR control
    • F02D41/0072—Estimating, calculating or determining the EGR rate, amount or flow

Definitions

  • the invention relates to a method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine.
  • EP 0 886 725 B1 discloses a method for determining an estimated value of a mass flow in the cylinders of an internal combustion engine.
  • the estimated value of the mass flow in the cylinders of the internal combustion engine is determined depending on a measured value of a mass flow upstream of a throttle valve in the intake channel, on the degree of opening of the throttle valve, on the rotational speed, on the crankshaft, on a measured value of the induction manifold pressure, and on further operating variables of the internal combustion engine.
  • a dynamic model of the intake channel of the internal combustion engine is provided for this purpose.
  • the dynamic model is corrected during operation, depending on the measured value of the mass flow in the intake channel and on a difference between a measured value and an estimated value of the induction manifold pressure, which difference is supplied to a controller, whose manipulated variable is used for correcting the dynamic model of the intake channel.
  • the invention addresses the problem of establishing a method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine, which method is also highly precise when pulsations of the mass flow occur in the intake channel.
  • the problem can be solved by a method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine, comprising the steps of:
  • the manipulated variable can be calculated by multiplying the difference between the estimated value and the measured value of the induction manifold pressure by a correction factor, which factor is determined depending on the time-related change in the measured value of the induction manifold pressure.
  • the correction factor can be determined from a characteristic curve.
  • the manipulated variable can be corrected depending on a measured value of the air mass flow.
  • the manipulated variable can be determined depending on the integral of the difference between the estimated value and the measured value of the induction manifold pressure.
  • the object can also be achieved by a device for determining an estimated value of a mass flow in the intake channel of an internal combustion engine, comprising a sensor for measuring the value of an induction manifold pressure which is used as the command variable of a control loop.
  • the control loop may comprise an estimation unit for estimating the value of the induction manifold pressure which is used as a regulating variable of the control loop, wherein the estimation unit receives a manipulated variable of the control loop, a calculating unit for calculating the manipulated variable depending on the difference between the estimated value and a measured value of the induction manifold pressure and depending on the time-related change of the measured value of the induction manifold pressure, and a calculating unit for calculating the estimated value of the mass flow in the intake channel depending on the manipulated variable.
  • the calculating unit for calculating the manipulated variable may comprise a multiplier for multiplying the difference between the estimated value and the measured value of the induction manifold pressure by a correction factor, which factor is determined depending on the time-related change in the measured value of the induction manifold pressure.
  • the correction factor can be determined from a characteristic curve.
  • the device may further comprise a air mass flow sensor for providing a variable for correcting the manipulated variable.
  • the calculating unit for calculating the manipulated variable may comprise an integrator for determining the integral of the difference between the estimated value and the measured value of the induction manifold pressure.
  • FIG. 1 shows an internal combustion engine with a control unit
  • FIG. 2 shows a block schematic diagram of a part of the control unit, said part being relevant for the invention.
  • An internal combustion engine ( FIG. 1 ) includes an intake channel 1 , preferably with a throttle valve 10 , and with an engine block 2 , which has a cylinder 20 and a crankshaft 23 .
  • a piston 21 and a connecting rod 22 are assigned to the cylinder 20 .
  • the connecting rod 22 is connected to the piston and the crankshaft 23 .
  • a fuel injector 33 is additionally incorporated in the cylinder head 3 .
  • the fuel injector 33 can also be arranged in the intake channel 1 .
  • the internal combustion engine is shown in FIG. 1 with one cylinder. It can however include a plurality of cylinders.
  • An AGR valve 51 for setting the returned exhaust mass is arranged in the exhaust return 5 .
  • a mass flow meter, which captures an exhaust return mass flow M_EGR, can also be arranged in the exhaust return 5 if necessary.
  • the sensors comprise a pedal position sensor 71 which captures a pedal value of the accelerator pedal 7 ; a throttle valve position sensor 11 which captures a degree of opening of the throttle valve 10 ; an air mass meter 12 which captures an air mass flow; an induction manifold pressure sensor 13 which captures an induction manifold pressure in the intake channel 1 ; a temperature sensor 14 which captures the intake-air temperature; a rotational speed sensor 24 which captures the rotational speed of the crankshaft 23 ; and a temperature sensor 25 which captures a cooling-medium temperature.
  • any subsets of the aforementioned sensors or even additional sensors may be present.
  • the actuating systems comprise a servomechanism and an actuator in each case.
  • the servomechanism is an electromotive drive, an electromagnetic drive, a piezoelectric drive, or a further drive which is known to the person skilled in the art.
  • the actuators are designed as a throttle valve 10 , a fuel injector 33 or an EGR valve 51 .
  • references to the actuating systems also refer to the actuator which is assigned in each case.
  • the control unit 6 is preferably designed as an electronic engine control. However, it can also include a plurality of control devices which are electrically connected to each other, e.g. via a bus system.
  • a mass flow MAF_MAN within the intake channel 1 is corrected by adding the correction value COR which is described in detail below.
  • a gas mass MASS_MAN within the intake channel 1 is determined, depending on the corrected mass flow MAF_MAN_COR, by integrating the corrected mass flow MAF_MAN_COR over time.
  • a summing point S 2 the difference between the measured value MAP_MES and the estimated value MAP_EST of the induction manifold pressure is calculated. The difference is then integrated in a block B 4 , and the integrated value is then supplied to the summing point S 3 .
  • a value is determined which is characteristic of the change in the measured value MAP_MES of the induction manifold pressure.
  • the time-related derivative of the measured value MAP_MES of the induction manifold pressure is preferably determined in the block B 5 for this purpose.
  • This derivative then represents the input variable for a characteristic map, by means of which a correction factor FAC is determined in the block B 6 .
  • FAC correction factor
  • the blocks B 2 , B 3 , B 4 , B 5 , B 6 therefore form a control loop, in which the command variable is the measured value MAP_MES of the induction manifold pressure, in which the regulating variable is the estimated value MAP_EST of the induction manifold pressure, and in which the manipulated variable is the correction value COR, which is in turn corrected using the mass flow MAF_MAN within the intake channel 1 , thus producing the corrected mass flow MAF_MAN_COR within the intake channel 1 .
  • the correction factor FAC is determined in advance by means of tests at an engine test bench, or by means of simulation, and stored in the characteristic curve.
  • the estimated value MAF_EST can even be determined without the mass flow MAF_MAN within the intake channel.
  • the mass flow MAF_MAN within the intake channel is simply set to zero in this case, which corresponds to omitting the block B 1 . It is also possible, therefore, to determine a sufficiently precise estimated value MAF_EST of the mass flow in the intake channel in a simplified manner and without the calculations in the block B 1 .
  • an inclusion of the block B 1 has the advantage that, by calculating the mass flow MAF_MAN within the intake channel in the block B 1 , an approximate operating point is specified for the control loop as a form of advance control, and a precise estimated value MAF_EST of the mass flow in the intake channel is consequently provided more quickly, which is a significant advantage, particularly in the case of a dynamic running of the internal combustion engine.
  • the estimated value MAF_EST of the mass flow can then be used for the further calculation of actuating signals for actuators of the internal combustion engine, or also for diagnosis.
US10/624,416 2001-01-23 2003-07-22 Method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine Expired - Fee Related US6985806B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10102914A DE10102914C1 (de) 2001-01-23 2001-01-23 Verfahren zum Ermitteln eines Schätzwertes eines Massenstroms in den Ansaugtrakt einer Brennkraftmaschine
DE10102914.4 2001-01-23
PCT/DE2001/004929 WO2002059471A1 (de) 2001-01-23 2001-12-27 Verfahren zum ermitteln eines schätzwertes eines massenstroms in den ansaugtrakt einer brennkraftmaschine

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2001/004929 Continuation WO2002059471A1 (de) 2001-01-23 2001-12-27 Verfahren zum ermitteln eines schätzwertes eines massenstroms in den ansaugtrakt einer brennkraftmaschine

Publications (2)

Publication Number Publication Date
US20050021215A1 US20050021215A1 (en) 2005-01-27
US6985806B2 true US6985806B2 (en) 2006-01-10

Family

ID=7671463

Family Applications (1)

Application Number Title Priority Date Filing Date
US10/624,416 Expired - Fee Related US6985806B2 (en) 2001-01-23 2003-07-22 Method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine

Country Status (4)

Country Link
US (1) US6985806B2 (pl)
EP (1) EP1362173B1 (pl)
DE (2) DE10102914C1 (pl)
WO (1) WO2002059471A1 (pl)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060173607A1 (en) * 2003-03-03 2006-08-03 Noritaka Matsuo Engine suction air flow rate measuring device
US7139656B1 (en) * 2005-12-14 2006-11-21 Gm Global Technology Operations, Inc. Mass airflow rate per cylinder estimation without volumetric efficiency map
US20080004787A1 (en) * 2004-07-09 2008-01-03 Denso Corporation Air-fuel ratio controller for internal combustion engine and diagnosis apparatus for intake sensors
US20080229816A1 (en) * 2005-09-29 2008-09-25 Bayerische Motoren Werke Device for Pressure-Based Load Detection
US20090157280A1 (en) * 2006-07-28 2009-06-18 Thomas Burkhardt Method and device for operating an internal combustion engine
US20100185379A1 (en) * 2007-05-23 2010-07-22 Thomas Burkhardt Method and device for operating an internal combustion engine
US20120158374A1 (en) * 2010-12-17 2012-06-21 Delphi Technologies, Inc. Method for real-time modeling of an n-dimensional surface
US20140336903A1 (en) * 2012-01-18 2014-11-13 International Engine Intellectual Property Company, Llc Mass airflow sensor calibration evaluation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4029739B2 (ja) 2003-02-05 2008-01-09 トヨタ自動車株式会社 内燃機関における充填空気量演算
EP2098710B1 (en) * 2008-03-04 2016-07-27 GM Global Technology Operations LLC A method for estimating the oxygen concentration in internal combustion engines

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH025734A (ja) * 1988-06-24 1990-01-10 Hitachi Ltd 内燃機関用補助空気供給装置の制御方法
DE3938898A1 (de) 1989-11-24 1991-05-29 Sartorius Gmbh Verfahren und vorrichtung zum pulsationsfreien kontinuierlichen gravimetrischen dosieren
US5094213A (en) 1991-02-12 1992-03-10 General Motors Corporation Method for predicting R-step ahead engine state measurements
US5205260A (en) 1991-04-10 1993-04-27 Hitachi, Ltd. Method for detecting cylinder air amount introduced into cylinder of internal combustion engine with exhaust gas recirculation system and for controlling fuel injection
JPH09228884A (ja) * 1996-02-20 1997-09-02 Toyota Motor Corp 内燃機関の制御装置
WO1997035106A2 (de) 1996-03-15 1997-09-25 Siemens Aktiengesellschaft Verfahren zum modellgestützten bestimmen der in die zylinder einer brennkraftmaschine einströmenden frischluftmasse bei externer abgasrückführung
US5889204A (en) * 1996-04-19 1999-03-30 Daimler-Benz Ag Device for determining the engine load for an internal combustion engine
DE19844637C1 (de) 1998-09-29 1999-10-14 Siemens Ag Einrichtung zum Steuern einer Brennkraftmaschine
DE19825305A1 (de) 1998-06-05 1999-12-09 Bayerische Motoren Werke Ag Verfahren zur Korrektur der durch ein Saugrohr angesaugten und im Saugrohr gemessenen Luftmasse eines Verbrennungsmotors
US6697729B2 (en) * 2002-04-08 2004-02-24 Cummins, Inc. System for estimating NOx content of exhaust gas produced by an internal combustion engine

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH025734A (ja) * 1988-06-24 1990-01-10 Hitachi Ltd 内燃機関用補助空気供給装置の制御方法
DE3938898A1 (de) 1989-11-24 1991-05-29 Sartorius Gmbh Verfahren und vorrichtung zum pulsationsfreien kontinuierlichen gravimetrischen dosieren
US5094213A (en) 1991-02-12 1992-03-10 General Motors Corporation Method for predicting R-step ahead engine state measurements
US5205260A (en) 1991-04-10 1993-04-27 Hitachi, Ltd. Method for detecting cylinder air amount introduced into cylinder of internal combustion engine with exhaust gas recirculation system and for controlling fuel injection
JPH09228884A (ja) * 1996-02-20 1997-09-02 Toyota Motor Corp 内燃機関の制御装置
WO1997035106A2 (de) 1996-03-15 1997-09-25 Siemens Aktiengesellschaft Verfahren zum modellgestützten bestimmen der in die zylinder einer brennkraftmaschine einströmenden frischluftmasse bei externer abgasrückführung
EP0886725B1 (de) 1996-03-15 1999-08-25 Siemens Aktiengesellschaft Verfahren zum modellgestützten bestimmen der in die zylinder einer brennkraftmaschine einströmenden frischluftmasse bei externer abgasrückführung
US5889204A (en) * 1996-04-19 1999-03-30 Daimler-Benz Ag Device for determining the engine load for an internal combustion engine
DE19825305A1 (de) 1998-06-05 1999-12-09 Bayerische Motoren Werke Ag Verfahren zur Korrektur der durch ein Saugrohr angesaugten und im Saugrohr gemessenen Luftmasse eines Verbrennungsmotors
DE19844637C1 (de) 1998-09-29 1999-10-14 Siemens Ag Einrichtung zum Steuern einer Brennkraftmaschine
US6697729B2 (en) * 2002-04-08 2004-02-24 Cummins, Inc. System for estimating NOx content of exhaust gas produced by an internal combustion engine

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7204134B2 (en) * 2003-03-03 2007-04-17 Noritaka Matsuo Engine suction air flow rate measuring device
US20060173607A1 (en) * 2003-03-03 2006-08-03 Noritaka Matsuo Engine suction air flow rate measuring device
US7631550B2 (en) * 2004-07-09 2009-12-15 Denso Corporation Air-fuel ratio controller for internal combustion engine and diagnosis apparatus for intake sensors
US7677091B2 (en) 2004-07-09 2010-03-16 Denso Corporation Air-fuel ratio controller for an internal combustion engine and diagnosis apparatus for intake sensors
US20080004787A1 (en) * 2004-07-09 2008-01-03 Denso Corporation Air-fuel ratio controller for internal combustion engine and diagnosis apparatus for intake sensors
US20080275623A1 (en) * 2004-07-09 2008-11-06 Denso Corporation Air-fuel ratio controller for an internal combustion engine and diagnosis apparatus for intake sensors
US20080229816A1 (en) * 2005-09-29 2008-09-25 Bayerische Motoren Werke Device for Pressure-Based Load Detection
US7546760B2 (en) 2005-09-29 2009-06-16 Bayerische Motoren Werke Aktiengesellschaft Device for pressure-based load detection
US7139656B1 (en) * 2005-12-14 2006-11-21 Gm Global Technology Operations, Inc. Mass airflow rate per cylinder estimation without volumetric efficiency map
US20090157280A1 (en) * 2006-07-28 2009-06-18 Thomas Burkhardt Method and device for operating an internal combustion engine
US8489307B2 (en) * 2006-07-28 2013-07-16 Continental Automotive Gmbh Method and device for operating an internal combustion engine
US20100185379A1 (en) * 2007-05-23 2010-07-22 Thomas Burkhardt Method and device for operating an internal combustion engine
US8412437B2 (en) 2007-05-23 2013-04-02 Continental Automotive Gmbh Method and device for operating an internal combustion engine
US20120158374A1 (en) * 2010-12-17 2012-06-21 Delphi Technologies, Inc. Method for real-time modeling of an n-dimensional surface
US8650011B2 (en) * 2010-12-17 2014-02-11 Delphi Technologies, Inc. Method for determining an engine response characteristic
US20140336903A1 (en) * 2012-01-18 2014-11-13 International Engine Intellectual Property Company, Llc Mass airflow sensor calibration evaluation
US9175623B2 (en) * 2012-01-18 2015-11-03 International Engine Intellectual Property Company, Llc Mass airflow sensor calibration evaluation

Also Published As

Publication number Publication date
EP1362173B1 (de) 2004-07-21
US20050021215A1 (en) 2005-01-27
WO2002059471A1 (de) 2002-08-01
DE10102914C1 (de) 2002-08-08
EP1362173A1 (de) 2003-11-19
DE50102950D1 (de) 2004-08-26

Similar Documents

Publication Publication Date Title
US7441544B2 (en) Control device for internal combustion engine
US7318342B2 (en) Method for model-based determination of the fresh air mass flowing into the cylinder combustion chamber of an internal combustion engine during an intake phase
US7438061B2 (en) Method and apparatus for estimating exhaust pressure of an internal combustion engine
US6321732B1 (en) Air flow and EGR flow estimation
US6698203B2 (en) System for estimating absolute boost pressure in a turbocharged internal combustion engine
US7100375B2 (en) System for limiting rotational speed of a turbocharger
US6715287B1 (en) Method and device for controlling an internal combustion engine that is provided with an air system
EP0478120B1 (en) Method and apparatus for inferring barometric pressure surrounding an internal combustion engine
US6352065B1 (en) Method and device for determining the gas intake in an internal combustion engine
EP0845587A2 (en) Internal combustion engine intake port flow determination
US6539714B1 (en) System for estimating turbocharger rotational speed
US6909961B2 (en) Method and device for measuring a temperature variable in a mass flow pipe
EP0476811B1 (en) Method and apparatus for controlling an internal combustion engine
US6615812B2 (en) Method and arrangement for operating an internal combustion engine
US6985806B2 (en) Method for determining an estimated value of a mass flow in the intake channel of an internal combustion engine
EP2924272A1 (en) Control device of internal combustion engine
US6655201B2 (en) Elimination of mass air flow sensor using stochastic estimation techniques
EP2052144A1 (en) Apparatus for and method of controlling internal combustion engine equipped with turbocharger
JP4689678B2 (ja) エンジンのポンピング・トルクを推定する方法
US7546760B2 (en) Device for pressure-based load detection
US4982714A (en) Air-fuel control apparatus for an internal combustion engine
JPH11351010A (ja) 過給機付き内燃機関
JP2595148B2 (ja) 内燃機関制御装置
JP3627462B2 (ja) 内燃機関の制御装置
EP1559891A1 (en) Turbocharged engine control method having improved smoke control

Legal Events

Date Code Title Description
AS Assignment

Owner name: SIEMENS AKTIENGESELLSCHAFT, GERMANY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:STADLER, WOLFGANG;REEL/FRAME:014780/0906

Effective date: 20030630

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20100110